The phytopathogenic fungus Ashbya gossypii is a filamentously growing ascomycete that was first isolated as a plant pathogen in tropical and sub-tropical regions. It infects the seed capsule of cotton plants and has also been isolated from tomatoes and citrus fruits. The infection of the seed capsule is caused by transmission of A. gossypii mycelium pieces or spores by stinging-sucking insects and causes a disease called stigmatomycosis. Presently, A. gossypii represents the most compact eukaryotic genome, compared to genome sizes of 12.5 Mb for S. cerevisiae (Chu et al., 1986), 31.0 Mb for Aspergillus nidulans (Brody and Carbon, 1989) and 47.0 Mb for Neurospora crassa (Orbach et al., 1988).
A. gossypii is systematically grouped to the endomycetales belonging to the family of spermophthoraceae. This classification is based on the observation that the spores that develop in hyphal compartments called sporangia look like ascospores, which are defined as endproducts of meiosis.
Since Ashbya gossypii is a filamentous ascomycete, and is capable of growing only by filamentous (hyphal) growth, fungal targets found in this model organism are predictive of targets which will be found in other pathogens, the vast majority of which grow in a filamentous fashion.